The present invention relates to optical storage media. In particular, the present invention relates to an optical storage medium including an agent that renders the optical storage medium unreadable after a preselected period of time.
Optical storage media are well known in the art. Optical storage media, such as audio and/or visual compact discs (CD) or digital versatile discs (DVD), permit large amounts of data or information to be stored and retrieved. Because of their capacity to store large amounts of data, optical storage media have become enormously popular in the content media industry for delivering computer software, compilations of music, movies, and other types of audio and/or visual materials to the consumer.
Typically,data stored in an optical storage medium remains available to the consumer without any practical limit as to the length of time over which the data may be read. Being most of the time read only memory, there are no software limitations introduced in the data to otherwise prevent or limit the availability or readability of the data. However, the absence of any limit to the availability or readability of the data is a drawback in some cases.
A significant factor contributing to the price charged for an optical storage medium is the useful life of the data stored thereon. Because the data remains available for the life of the particular optical storage medium, the data may be repeatedly copied by the consumer without remitting any payment to the content media distributor or royalties to the author of the work or data. As a result, significant monies may be lost due to the length of time over which the data is available. Although the risk that the data may be repeatedly copied is typically passed on to the consumer in the form of higher prices for the sale or rental of the optical storage medium, the higher prices do little to curtail copying. However, by controlling the useful life or the availability of the data, there is the potential to create a new revenue stream in repeat purchases (similar to rentals) of optical storage media.
Accordingly, it is desirable to provide an optical storage medium having limited useful life. In particular, it is desired to provide an optical storage medium to control the period over which the data stored in the optical storage medium becomes unreadable.
In a preferred embodiment, the invention comprises an optical storage medium comprising a substrate supporting a data storage layer for storing optically readable data. A reservoir is attached to the substrate for storing a chemical agent. The reservoir is rupturable to release the chemical agent when subjected to an applied force. The reservoir is located in proximity to the data storage layer to permit the chemical agent released from the reservoir upon rupture to contact the data storage layer.
In a narrower aspect of the invention, the invention comprises an optical storage medium as described above, and a substantially airtight container having an interior in which the substrate and attached reservoir are housed. The interior of the container is under a vacuum. The container includes a lid having an opening sealed by a frangible seal for admitting air under atmospheric pressure into the interior when the frangible seal is broken. The atmospheric pressure exerts a force on the reservoir sufficient to rupture the reservoir and release the chemical agent.
In a different aspect of the invention, the invention comprises an optical storage medium including a substrate supporting a metallic data storage layer for storing optically readable data, a reservoir located in proximity to the data storage layer for storing a chemical agent in contact with the data storage layer on a first side of the reservoir, and a flexible metallic lamina in contact with the chemical agent on an opposite side of the reservoir. The lamina is more electronegative than the data storage layer. A nonconductive member is located intermediate the data storage layer and the lamina for holding apart the data storage layer and the lamina. The nonconductive member has at least a portion through which the lamina can be deformed and come into contact with the data storage layer to complete a voltaic circuit from the data storage layer through the chemical agent to the lamina. As a result, the material of the data storage layer will degrade over time due to voltaic action.